week_9_lecture_1

G sv40 enhancer 200bp upstream 2 x 72bp sequences

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Unformatted text preview: (i.e. general transcription factors) transcription - e.g. Sp1 binds to GC boxes e.g. and can be used to assemble TFIID at a TATA-less promoter through interaction with a TAF with ENHANCERS SV40 promoter • • • • • in addition to upstream elements found in promoter (found within a in few 100 bp of start site) other sequences called enhancers can enhancers increase promoter activity increase Enhancers: orientation & position independent; therefore, distinct Enhancers: from promoter from e.g. SV40 enhancer: ~200bp upstream, 2 X 72bp sequences required e.g. for high level transcription (many binding sites) for Mutational analysis of SV40 enhancer uncovered high density of Mutational elements (more so than β -globin promoter) Enhancers often contain same elements as found in promoters, (e.g. Enhancers octamer) octamer) IG γ 2b H-CHAIN ENHANCER Protein gel Northern Weaver 2002 Molecular Biology Ed. 2 X: cutting sites for XbaI No No expression expression • Enhancers can Enhancers confer tissueconfer specific specific transcription transcription • E.g. Ig genes Ig carry enhancers within introns enhancers only active in B lymphocytes lymphocytes • Deletion of Deletion enhancers reduces Ig expression expression ORIENTATION-INDEPENDENT & POSITIONORIENTATION-INDEPENDENT INDEPENDENT ENHANCER H-chain H-chain enhancer enhancer Protein gel Weaver 2002 Molecular Biology Ed. 2 • H-chain enhancer (X2-X3 region) reinserted into Ig gene in different orientations & different places with respect to Ig γ 2b gene • No change in Ig expression: H-chain enhancer No activity orientation & position independent activity...
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This note was uploaded on 03/26/2014 for the course MBB 321 taught by Professor Davidson during the Spring '11 term at Simon Fraser.

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